This invention relates to a method for making curved hose.
Rubber hoses of curved shape are required in a variety of applications. An example of a curved hose is automotive radiator coolant hose. The customary method of making this hose is to extrude a tube, apply a reinforcement to the tube and extrude a cover layer over the reinforcement. The resulting uncured hose is cut to length and placed manually on mandrels having the shape of the desired finished hose configuration. The mandrels and the uncured hose assemblies are placed in a vulcanization unit. Here the lengths of hose are vulcanized on the mandrels in the desired configuration. The finished hose is then removed from the mandrel.
In making such curved pieces of hose, a large amount of manual work is carried out. Loading of the hose assembly onto the mandrel, though eased by the use of a considerable quantity of lubricant, is difficult. Upon unloading the hose from the mandrel, the interior wall of the hose may rip or tear.
It has been proposed, in U.S. Pat. No. 4,110,396, to employ a mandrel having a "mechanical memory", i.e. a mandrel which may be mechanically deformed to a desired shape and which, upon heating, changes its shape to a preselected shape. Although this method alleviates or abolishes many of the problems normally associated with the use of a rigid mandrel, this method is not well adapted to mechanized production of curved rubber hose.
A relatively automatic and continuous process for making curved rubber hose is described in U.S. Pat. No. 4,118,162. In this process, a plurality of flexible mandrels are conveyed from a mandrel magazine in end-to-end fashion to a first extruder which covers the flexible mandrels with a rubber layer. A reinforcing thread is wrapped over the rubber layer and a second rubber layer is then extruded over the thread. Each individual mandrel is cut off from the line together with the rubber mix surrounding it. Each mandrel, and its associated rubber mix is bent to a desired shape and the rubber is then vulcanized. Following vulcanization, the mandrel is removed and returned to the mandrel magazine. It appears that this method can only be used to produce hose having a single curve in only one plane.
It is, therefore, an object of the present invention to provide a novel process for making curved rubber hose.
Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art from a reading of the detailed description which follows, the appended claims and the attached drawing.